(1) Field of the Invention
The present invention related to an alumina/titanium carbide ceramic sintered body to be used, for example, as a substrate for a thin film head, and a process for the preparation of this ceramic sintered body.
(2) Description of the Related Art
A thin film head has attracted attention as a high-density recording head that can be used instead of the head formed of ferrite or Sendust, a substrate for this thin film head is required to have a following characteristics:
(1) The abrasion resistance is excellent. PA1 (2) The surface smoothness is excellent. PA1 (3) The chipping resistance is excellent. PA1 (4) The machinability is excellent.
An alumina (Al.sub.2 O.sub.3)/titanium carbide (TiC) ceramic sintered body attracts attention as the material satisfying these requirements.
When this ceramic sintered body is used, the abrasion characteristic (1) can easily be obtained, but it is difficult to obtain the characteristics (2), (3) and (4).
As the means for improving the machinability of this ceramic sintered body, U.S. Pat. No. 4,582,812 discloses a magnetic head slider comprising a substrate consisting essentially of (a) 100 parts by weight consisting of aluminum oxide and 30 to 50 parts by weight of (TiC+TiO.sub.2), and provided that TiO.sub.2 /(TiC+TiO.sub.2).times.100=5 to 15%, (b) greater than one to 5 parts by weight of a machinability agent which is MgO, NiO, Cr.sub.2 O.sub.3 or ZrO.sub.2, and (c) 0.05 to 2 parts by weight of Y.sub.2 O.sub.3.
Furthermore, U.S. Pat. No. 4,598,052 discloses an alumina/titanium carbide/titanium oxide sintered body comprising 0.2 to 2 parts of a spinel of magnesium oxide and Al.sub.2 O.sub.3, 0.2 to 2 parts by weight of zirconium oxide and 0.05 to 2 parts by weight of yttrium oxide.
In the Al.sub.2 O.sub.3 /TiC ceramic sintered body having the above-mentioned structure is improved in the chipping resistance (3) and the machinability (4), but the surface smoothness (2) tends to degrade. Accordingly, in the case where the air bearing surface (ABS) of the substrate is subjected to the mirror polishing, in order to control falling of grains, the mirror polishing conditions should be moderated, and thereof, the polishing quantity per unit time decreases and the mirror polishing time becomes long, with the result that the manufacturing efficiency tends to decrease.